| 摘要 |
A composition comprising an azo compound in the form of granules with size ranging between 200 mu m and 10 mm and where the cumulative volume of pores ranges between 0.2 and 2 ml/g. The composition is used for controlling the characteristics of a cooling liquid. The azo compound is of formula (I): R<1> - R<4> = 1-6C alkyl group, optionally substituted by a hydroxy, alkoxy, carboxy or by a halogen atom; or 3-6C cycloalkyl group, optionally substituted by a hydroxy, alkoxy, carboxy group or by a halogen atom; or an aryl group such as phenyl or naphthyl, optionally substituted by one or more alkyl, alkoxy, hydroxy, carboxy groups or halogen atoms. At least one of the combination R1 with R2 and R3 with R4 form a cycloalkyl radical with the carbon atom to which they are attached. An Independent claim is made for a method for preparing the composition comprising: (i) humidification of the resulting powder by drying the suspension resulting from the final step of the synthesis of the azo compound, so as to obtain a powder containing 10-45% water, preferably 15-40%. (ii) grinding of the humidified powder under mechanical load through a channel of thickness e and perforation diameter d of ratio e/d = 0.5-3, or preferably 0.5-2, the diameter d being close to the desired size for the granules and thee load being such that the temperature of the powder remains at 40 deg C, preferably 30 deg C. (iii) drying the granules at a temperature of 45 deg C, preferably 35 deg C. |
